/**
 * Copyright (C) 2008 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.inject.internal;

import static com.google.common.base.Preconditions.checkState;
import static com.google.inject.Scopes.SINGLETON;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.inject.Binder;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.Module;
import com.google.inject.Provider;
import com.google.inject.Singleton;
import com.google.inject.Stage;
import com.google.inject.internal.InjectorImpl.InjectorOptions;
import com.google.inject.internal.util.SourceProvider;
import com.google.inject.internal.util.Stopwatch;
import com.google.inject.spi.Dependency;
import com.google.inject.spi.Element;
import com.google.inject.spi.Elements;
import com.google.inject.spi.InjectionPoint;
import com.google.inject.spi.ModuleAnnotatedMethodScannerBinding;
import com.google.inject.spi.PrivateElements;
import com.google.inject.spi.ProvisionListenerBinding;
import com.google.inject.spi.TypeListenerBinding;

import java.util.List;
import java.util.logging.Logger;

/**
 * A partially-initialized injector. See {@link InternalInjectorCreator}, which
 * uses this to build a tree of injectors in batch.
 * 
 * @author jessewilson@google.com (Jesse Wilson)
 */
final class InjectorShell {

    private final List<Element> elements;
    private final InjectorImpl injector;

    private InjectorShell(Builder builder, List<Element> elements, InjectorImpl injector) {
        this.elements = elements;
        this.injector = injector;
    }

    InjectorImpl getInjector() {
        return injector;
    }

    List<Element> getElements() {
        return elements;
    }

    static class Builder {
        private final List<Element> elements = Lists.newArrayList();
        private final List<Module> modules = Lists.newArrayList();

        /** lazily constructed */
        private State state;

        private InjectorImpl parent;
        private InjectorOptions options;
        private Stage stage;

        /** null unless this exists in a {@link Binder#newPrivateBinder private environment} */
        private PrivateElementsImpl privateElements;

        Builder stage(Stage stage) {
            this.stage = stage;
            return this;
        }

        Builder parent(InjectorImpl parent) {
            this.parent = parent;
            this.state = new InheritingState(parent.state);
            this.options = parent.options;
            this.stage = options.stage;
            return this;
        }

        Builder privateElements(PrivateElements privateElements) {
            this.privateElements = (PrivateElementsImpl) privateElements;
            this.elements.addAll(privateElements.getElements());
            return this;
        }

        void addModules(Iterable<? extends Module> modules) {
            for (Module module : modules) {
                this.modules.add(module);
            }
        }

        Stage getStage() {
            return options.stage;
        }

        /** Synchronize on this before calling {@link #build}. */
        Object lock() {
            return getState().lock();
        }

        /**
         * Creates and returns the injector shells for the current modules. Multiple shells will be
         * returned if any modules contain {@link Binder#newPrivateBinder private environments}. The
         * primary injector will be first in the returned list.
         */
        List<InjectorShell> build(Initializer initializer, ProcessedBindingData bindingData, Stopwatch stopwatch, Errors errors) {
            checkState(stage != null, "Stage not initialized");
            checkState(privateElements == null || parent != null, "PrivateElements with no parent");
            checkState(state != null, "no state. Did you remember to lock() ?");

            // bind Singleton if this is a top-level injector
            if (parent == null) {
                modules.add(0, new RootModule());
            } else {
                modules.add(0, new InheritedScannersModule(parent.state));
            }
            elements.addAll(Elements.getElements(stage, modules));

            // Look for injector-changing options
            InjectorOptionsProcessor optionsProcessor = new InjectorOptionsProcessor(errors);
            optionsProcessor.process(null, elements);
            options = optionsProcessor.getOptions(stage, options);

            InjectorImpl injector = new InjectorImpl(parent, state, options);
            if (privateElements != null) {
                privateElements.initInjector(injector);
            }

            // add default type converters if this is a top-level injector
            if (parent == null) {
                TypeConverterBindingProcessor.prepareBuiltInConverters(injector);
            }

            stopwatch.resetAndLog("Module execution");

            new MessageProcessor(errors).process(injector, elements);

            /*if[AOP]*/
            new InterceptorBindingProcessor(errors).process(injector, elements);
            stopwatch.resetAndLog("Interceptors creation");
            /*end[AOP]*/

            new ListenerBindingProcessor(errors).process(injector, elements);
            List<TypeListenerBinding> typeListenerBindings = injector.state.getTypeListenerBindings();
            injector.membersInjectorStore = new MembersInjectorStore(injector, typeListenerBindings);
            List<ProvisionListenerBinding> provisionListenerBindings = injector.state.getProvisionListenerBindings();
            injector.provisionListenerStore = new ProvisionListenerCallbackStore(provisionListenerBindings);
            stopwatch.resetAndLog("TypeListeners & ProvisionListener creation");

            new ScopeBindingProcessor(errors).process(injector, elements);
            stopwatch.resetAndLog("Scopes creation");

            new TypeConverterBindingProcessor(errors).process(injector, elements);
            stopwatch.resetAndLog("Converters creation");

            bindStage(injector, stage);
            bindInjector(injector);
            bindLogger(injector);

            // Process all normal bindings, then UntargettedBindings.
            // This is necessary because UntargettedBindings can create JIT bindings
            // and need all their other dependencies set up ahead of time.
            new BindingProcessor(errors, initializer, bindingData).process(injector, elements);
            new UntargettedBindingProcessor(errors, bindingData).process(injector, elements);
            stopwatch.resetAndLog("Binding creation");

            new ModuleAnnotatedMethodScannerProcessor(errors).process(injector, elements);
            stopwatch.resetAndLog("Module annotated method scanners creation");

            List<InjectorShell> injectorShells = Lists.newArrayList();
            injectorShells.add(new InjectorShell(this, elements, injector));

            // recursively build child shells
            PrivateElementProcessor processor = new PrivateElementProcessor(errors);
            processor.process(injector, elements);
            for (Builder builder : processor.getInjectorShellBuilders()) {
                injectorShells.addAll(builder.build(initializer, bindingData, stopwatch, errors));
            }
            stopwatch.resetAndLog("Private environment creation");

            return injectorShells;
        }

        private State getState() {
            if (state == null) {
                state = new InheritingState(State.NONE);
            }
            return state;
        }
    }

    /**
     * The Injector is a special case because we allow both parent and child injectors to both have
     * a binding for that key.
     */
    private static void bindInjector(InjectorImpl injector) {
        Key<Injector> key = Key.get(Injector.class);
        InjectorFactory injectorFactory = new InjectorFactory(injector);
        injector.state.putBinding(key, new ProviderInstanceBindingImpl<Injector>(injector, key, SourceProvider.UNKNOWN_SOURCE, injectorFactory, Scoping.UNSCOPED, injectorFactory, ImmutableSet.<InjectionPoint> of()));
    }

    private static class InjectorFactory implements InternalFactory<Injector>, Provider<Injector> {
        private final Injector injector;

        private InjectorFactory(Injector injector) {
            this.injector = injector;
        }

        public Injector get(Errors errors, InternalContext context, Dependency<?> dependency, boolean linked) throws ErrorsException {
            return injector;
        }

        public Injector get() {
            return injector;
        }

        public String toString() {
            return "Provider<Injector>";
        }
    }

    /**
     * The Logger is a special case because it knows the injection point of the injected member. It's
     * the only binding that does this.
     */
    private static void bindLogger(InjectorImpl injector) {
        Key<Logger> key = Key.get(Logger.class);
        LoggerFactory loggerFactory = new LoggerFactory();
        injector.state.putBinding(key, new ProviderInstanceBindingImpl<Logger>(injector, key, SourceProvider.UNKNOWN_SOURCE, loggerFactory, Scoping.UNSCOPED, loggerFactory, ImmutableSet.<InjectionPoint> of()));
    }

    private static class LoggerFactory implements InternalFactory<Logger>, Provider<Logger> {
        public Logger get(Errors errors, InternalContext context, Dependency<?> dependency, boolean linked) {
            InjectionPoint injectionPoint = dependency.getInjectionPoint();
            return injectionPoint == null ? Logger.getAnonymousLogger() : Logger.getLogger(injectionPoint.getMember().getDeclaringClass().getName());
        }

        public Logger get() {
            return Logger.getAnonymousLogger();
        }

        public String toString() {
            return "Provider<Logger>";
        }
    }

    private static void bindStage(InjectorImpl injector, Stage stage) {
        Key<Stage> key = Key.get(Stage.class);
        InstanceBindingImpl<Stage> stageBinding = new InstanceBindingImpl<Stage>(injector, key, SourceProvider.UNKNOWN_SOURCE, new ConstantFactory<Stage>(Initializables.of(stage)), ImmutableSet.<InjectionPoint> of(), stage);
        injector.state.putBinding(key, stageBinding);
    }

    private static class RootModule implements Module {
        public void configure(Binder binder) {
            binder = binder.withSource(SourceProvider.UNKNOWN_SOURCE);
            binder.bindScope(Singleton.class, SINGLETON);
            binder.bindScope(javax.inject.Singleton.class, SINGLETON);
        }
    }

    private static class InheritedScannersModule implements Module {
        private final State state;

        InheritedScannersModule(State state) {
            this.state = state;
        }

        public void configure(Binder binder) {
            for (ModuleAnnotatedMethodScannerBinding binding : state.getScannerBindings()) {
                binding.applyTo(binder);
            }
        }
    }
}
